Each EUM application can register up to 500 AJAX page names by default. If the AJAX requests are overflowing, this will limit all of the new AJAX requests that are not already registered with a page and they will get dropped on the EUM side.
This can be seen in the eum-processor.log if the logging is set to DEBUG in EUM/eum-procesor/bin/logback.xml.
2. The max AJAX limit is getting hit.
The code example below limits the number ofAJAX request per base or virtual page to 7.
3. The page is navigating to another page before the Adrum beacon is posted.
There can be situations when the base page or user triggered an AJAX call but, before the beacon reports it back to the EUM collector, the page redirects or the user navigates to another page and the last beacon gets aborted.
Little can be done since the browser will abort any pending requests in such cases, but you can turn off the buffer. By default, the beacon buffers 20 requests before going out or 5 seconds (whichever occurs first).
Similar to case 3, if the AJAX causes a redirect to another page, the beacon for the AJAX will not be prepared and it will be aborted.
5. The Async request is done through the FETCH API
The Fetch API provides an interface for fetching resources (including across the network). It will seem familiar to anyone who has used XMLHttpRequest, but the new API provides a more powerful and flexible feature set.